There are hundreds of restricted airspace regions and flying zones all over the world. Some examples include the White House in the U.S., the Rashtrapathi Bhavan in India, and various military installations.
Restricted areas cover regions within which the flight of aircraft, while not wholly prohibited, is subject to restrictions. Restricted areas typically include hazards to aircraft such as artillery firing, aerial gunnery, or guided missiles. As such, penetration by the aircraft of restricted areas without authorization may be extremely hazardous to the aircraft and its occupants.
Hundreds of pilots inadvertently enter restricted airspace every year without any destructive intent. In many such cases, the plane may be gunned down or buildings within the restricted area may require unnecessary evacuation. In addition, if the plane is hijacked and is flown into a restricted area with the identifying transponder switched off, communication from the plane to air traffic control may be disabled.